The present invention relates generally to an apparatus for unlatching and entraining elevator car doors and shaft doors and, in particular, to such an apparatus having a pneumatic actuating system.
The French Patent Specification No. 1.005.032 shows an extendable and retractable entraining and unlatching device for an elevator system. The retraction and unlatching is caused by the excitation of two electromagnets against the force of a tension spring. The extension and latching is caused by turning off the electromagnets whereby the tension spring moves a lever system to raise the magnet armatures and push the entraining and unlatching element outwardly into the latched position.
This type of entraining and unlatching element has several moving parts which are subject to substantial wear, and are not easily accessible for maintenance and repairs. Furthermore, noise problems can arise in magnet actuated systems of this kind.